Climate change strengthens an army of forest-eating insects

By Rowena Lindsay
Hemlock woolly adelgids aren’t native to North America, but droves of them have settled into American forests where they threaten entire ecosystems.

A tiny bug, no bigger than a grain of pepper, is wreaking big-time havoc in US forests, and forest managers are scrambling to keep up.

Hemlock woolly adelgids aren’t native to North America, but droves of them have taken up residence in hemlock forests, from New England to the West Coast, thanks to increased trade and travel. Nestled under the needles of hemlock trees, the invasive insects cut off nutrients to the tree and can eventually take down trees that have stood for 300 years.

If left unchecked, the hemlock woolly adelgid and other pests are projected to put 63 percent of the nation’s forests at risk by 2027, according to a study published this year in the journal Ecological Applications. The tiny invaders could put several species of hemlock at risk for extinction, threatening the biodiversity and stability of ecosystems across the country and cutting a carbon sink for mitigating greenhouse gas emissions.

Globalization has opened the door for hundreds of invasive pests, from the Asian longhorned beetle to the emerald ash borer. And climate change, it seems, will make it even more difficult to evict them.